Tapeless super-absorbent disposable diaper

ABSTRACT

A disposable diaper which has a fluid permeable topsheet, a fluid permeable second sheet, a flexible absorbent body, a biodegradable, liquid impermeable barrier including side dams, and a soft, flexible backsheet. The topsheet can include leg cuffs that are an integral, rather than an adjunct, part of the topsheet. The diaper also has an attachment means for allowing the diaper to be secured about the wearer.

This application is a continuation-in-part of applicant's co-pendingU.S. application Ser. No. 07/374,506 filed Jun. 30, 1989, now U.S. Pat.No. 5,019,069, entitled "Tapeless Super-Absorbent Disposable Diaper."

BACKGROUND OF THE INVENTION

This invention generally relates to absorbent articles and, moreparticularly, to an improved disposable diaper for incontinent adultsand babies.

Infants and other incontinent persons wear disposable diapers to receiveand contain feces, urine and other fluid discharges from the body.Disposable diapers function both to contain the discharged materials andto isolate these materials from the body of the wearer and from thewearer's surroundings. Modern embodiments of disposable diaperfrequently perform these tasks in a manner superior to that oftraditional cloth diapers.

Prior art disposable diapers disclose three basic structural elements: afluid permeable topsheet designed to be placed next to the wearer'sskin; a backsheet which forms, in use, the outer surface of the diaper;and an absorbent element interposed between the topsheet and thebacksheet.

The topsheet in prior art diapers is permeable to fluids. The backsheetin prior art diapers is a usually liquid impermeable or repellant. Itsfunction is to contain fluids within the absorbent element therebyprotecting the wearer's outer garments and other surfaces from soilingby these fluids. Backsheets are commonly formed of a thin sheet ofpolyethylene, polypropylene or other flexible moisture impedingmaterials which are substantially water impervious. However, they arenot as soft to the touch as traditional cloth diapers. These materialsare also more susceptible to cuts or tears than traditional clothdiapers. One method for overcoming the susceptibility to cuts or tearsis to make a thicker backsheet. However, the thicker the backsheet is,the noisier and less biodegradable the disposable diaper is.

The absorbent core of prior art diapers is comprised of a mass ofhydrophilic fiber material. These fibers are often formed fromcellulose. The core is intended to absorb fluids that permeate thetopsheet.

In many disposable diapers, a liquid impermeable or repellant layer orthe backsheet is bonded to the inside ends of the absorbent core to formend-dams to prevent fluids from escaping the diaper at the waistline.The manufacturing process which produces the hourglass or form-fittingshape of modern disposable diapers creates the desired shape after allthe elements of the diaper have been assembled. This process generallyprecludes utilizing the liquid impermeable layer to form side-dams toprevent fluids from escaping the diaper in the leg area. The escape ofbody discharges in the leg area, however, is minimized by using elasticleg cuffs.

Instead of or in addition to an elastic leg cuff, some prior artdisposable diapers have standing leg cuffs to minimize the escape ofbody discharges in the leg area. Because of the manufacturing processwhich produces the hourglass or form-fitting shape, the standing legcuffs are separate units bonded to the topsheet.

Almost all prior art disposable diapers utilize tape fasteners attachedat the projections ("ears") formed by the widest portions of thehourglass shaped diaper to allow for securing the diaper about thewearer. Because the tape fasteners are indiscriminate as what they willstick to, they can stick to each other, the topsheet, other diapers orequipment during the manufacturing process resulting in unusable productor downtime in the manufacturer's machinery. Similarly, during use, thetapes can stick to areas of the diaper other than those intended andresult in an unusable diaper and customer dissatisfaction. In addition,tape fasteners are expensive and non-biodegradable.

SUMMARY

It is, therefore, an object of the present invention to provide animproved absorbent article that has standing leg cuffs. The standing legcuffs are an integral part, rather than an adjunct part, of thetopsheet.

Yet another object of the invention is to provide an attachment meansfor allowing the diaper to be secured about the wearer.

Therefore, in accordance with one aspect of the present invention, thereis disclosed an absorbent article comprising a fluid permeable topsheet,a flexible, absorbent body, a liquid impermeable barrier, and abacksheet comprising soft, flexible material. The impermeable barrier isa film of biodegradable material. In each leg area of the diaper, thetopsheet is folded back over itself and bonded thereto to form a casingfor elastic and a longitudinal flap which together function as a legcuff.

In another aspect of the present invention, there is disclosed adisposable diaper comprising a fluid permeable topsheet, an absorbentbody, a backsheet, and an attachment means for securing the diaper aboutits wearer. The means for securing the diaper is applied to one end ofthe backsheet and to the opposite side of the opposite end of thebacksheet.

Other and further objects, features and advantages of the presentinvention will be apparent from the following description of thepresently preferred embodiment of the invention in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of this invention which are believed to be novel are setforth with particularity in the appended claims. The invention itself,however, together with its objects and the advantages thereof, will bebest understood by reference to the following description taken inconnection with the accompanying drawings, in which:

FIG. 1 is an elevational view of a diaper of the invention;

FIG. 2 is an elevational view of a diaper of the invention with portionsthereof cut away to show inner detail;

FIG. 3 is a cross section taken along 3--3 of FIG. 2;

FIG. 4 is a longitudinal cross section along 4--4 of FIG. 2;

FIG. 5 is a cross section of an alternate embodiment along 3--3 of FIG.2 with leg flaps folded down; and

FIG. 6 is a cross section of an alternate embodiment along 3--3 of FIG.2 with leg flaps erect.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As used herein, the term "disposable absorbent article" refers toarticles which receive and contain feces, urine, blood, and other fluiddischarges from the body. These articles are intended to be discardedafter a single use rather than being laundered or otherwise restored andreused.

A "diaper" is a garment generally worn by infants and incontinentpersons. It should be understood, however, that while the presentinvention is discussed in terms of a diaper, it is also applicable touse in other disposable absorbent articles such as catamenial pads orbriefs, absorbent wound dressings and the like.

Referring now to the drawings and particularly to FIGS. 1 and 2, thepresent invention is generally indicated by the reference numeral 10 andgenerally includes a fluid permeable topsheet 11, a flexible, absorbentbody 13, a liquid impermeable barrier 17 and a backsheet 20. A preferreddiaper 10 also includes a fluid permeable second sheet 12 interposedbetween the topsheet 11 and the absorbent body 13.

The topsheet 11 is a relatively hydrophobic, substantially porous,non-woven material and permits a fluid to readily pass into theunderlying layers. Its hydrophobicity tends to cause the surface incontact with the wearer's skin to be dry and protected from fluidsabsorbed within the absorbent element. It can be made in part orcompletely of synthetic fibers such as polyester, polypropylene andrayon or natural fibers such as cotton. It can be made in a variety oflength and width dimensions but is preferably rectangular in shape.

In one embodiment shown in FIG. 3, the topsheet 11 is folded back overitself along each of its longitudinal edges and bonded thereto to formcasings 24 and an elastic band 23 is positioned within each casing. Thetopsheet 11 is again folded back over itself intermediate between thecenter of the topsheet and each longitudinal edge and bonded thereto toform flaps 25.

In an alternative embodiment shown in FIGS. 5 and 6, the topsheet 11 isfolded back over itself parallel to is longitudinal edges intermediatebetween said center and each said longitudinal edge and bonded theretoat least once to form both casings 24 and flaps 25. Those skilled in theart will recognize that at least one wide bond or two or more narrowerbonds are needed to form both the casings 24 and flaps 25. An elasticband 23 is positioned within each casing 24.

Each longitudinal flap in combination with the adjacent casing andelastic band will form or act as a standing leg cuff to minimize theescape of body discharges in the leg area. The topsheet 11 is bonded toitself by means generally not shown in the figures using any suitablemanner known in the art.

The second sheet 12 is substantially porous and permits a fluid toreadily pass into the underlying absorbent body 13. This sheet is moreor less hydrophobic in comparison with the absorbent body 13 of thediaper and prevents the rewetting of the topsheet 11 by the fluidcontained by the absorbent body 13. It can be made of synthetic ornatural fibers similar to the topsheet 11. In the preferred embodiment,the second sheet is made of adhesive bonded polypropylene. The secondsheet has length and width dimensions generally smaller than those ofthe topsheet.

The absorbent body 13 essentially contains hydrophilic fiber material.As shown more particularly in FIGS. 3 and 4, it preferably includes anabsorbent core 14, at least two super-absorbent zones 15 and at leastone wicking zone 16 positioned between the super-absorbent zones. Whilecomminuted wood pulp is preferred for the manufacture of the absorbentcore 14, a wide variety of absorbent materials commonly used indisposable absorbent articles, including foams, cellulose and absorbentpolymers, can also be used.

Each super-absorbent zone 15 contains super-absorbent hydrogel (SAH)material, preferably super-absorbent polymers (SAP). The SAH is at leastpartially integrated with materials, preferably, identical to those ofthe absorbent core 14. In the most preferred embodiment of the presentinvention, two super-absorbent zones 15 are completely surrounded by andarranged within the absorbent core 14 in substantially parallel zones.The super-absorbent zones 15 are separated by an absorbent area devoidof SAH and referred to as the wicking zone 16.

In the preferred embodiment, absorbent core 14 is folded or wrapped sothat the length and width dimensions of the absorbent body 13 are thesame or slightly smaller than the second sheet 12. The absorbent body 13has first and second side edges, 26 and 27 respectively.

The liquid impermeable barrier 17 is a thin film of polyethylene,polypropylene, or other flexible moisture impeding material which issubstantially water impervious. A biodegradable polyethylene orpolypropylene film with starch, carbon or other non-synthetic additivesintended to promote biodegradability can be used. A film formed from5-20% starch blended with polyethylene and having thickness of 0.6 to0.8 mil is preferred. As shown in FIGS. 3 and 4, the impermeable barrier17 folds and extends over the first and second side edges 26 and 27 ofthe absorbent body 13 forming side dams 19. Preferably the impermeablebarrier extends over the absorbent body 13 by 0.5 inches.

The backsheet 20 forms, in use, the outer surface of the diaper andprotects the impermeable barrier from cuts and tears. It can be made,exclusively or in combinations, of a wide variety of soft, flexiblematerials, including polyester, rayon, cotton, polyethylene andpolypropylene.

As shown in FIGS. 1 and 2, in the preferred embodiment of the diaper 10the backsheet 20 is cut in an hourglass or form-fitting shape. Itexceeds the width dimension of the topsheet 11 at the "ears" 22 ofbacksheet but is otherwise coextensive with the topsheet. The top sheet11 is affixed to the backsheet 20 by means generally not shown in thefigures using any suitable method known in the art.

The present invention also includes an attachment means for allowing thediaper 10 to be secured about its wearer. As shown in FIGS. 1 through 4,the preferred embodiment comprises at least one strip of attachmentmaterial applied to one end of the backsheet 20 and at least one otherstrip of the attachment applied to the opposite side of the opposite endof the backsheet 20.

In one embodiment, the attachment material is a biodegradable,selectively adhesive material. The selectively adhesive material can beselected from water-based latex adhesives, hot melt applicationparaffinor rubber-based adhesives or any other adhesive for which thecharacteristic of adhesion can be limited to contact with itself or someother selected adhesive. Preferably, the selectively adhesive materialis a rubber-based adhesive utilizing a styrene butadiene styrene systemsuch as H4012-01 from Findley Adhesives, Inc. and applied in a 1 to 2inch strip running the entire width of the backsheet 20. Thisapplication of adhesive may be direct, such as via transfer printing orhot melt extrusion, or it may be indirect via application of theadhesive using a film substrate which may be cut to size and bonded tothe backsheet

In another embodiment, the attachment material 21 is a hook and loopfastening system such as that produced under the Brand VELCRO.Preferably, the VELCRO is applied in a 0.5 to 2 inch strip running theentire width of the back sheet 20. The velcro is applied to thebacksheet 20 in any suitable manner known in the art.

The present invention, therefore, is well adapted to carry out theobjects and attain the ends and advantages mentioned as well as othersinherent therein. The novel features characteristic of this inventionare set forth in the appended claims. While a presently preferredembodiment of the invention has been given for the purpose ofdisclosure, various changes, modifications and alternative constructionsto the preferred embodiments described herein will be apparent to thoseskilled in the art. It should be understood, however, that there is notintention to limit the invention to the specific form disclosed. On thecontrary, the intention is to cover all modifications, alternatives,constructions and equivalents falling within the spirit and scope of theinvention.

What is claimed is:
 1. A disposable diaper, comprising:a fluid permeable topsheet, a backsheet and an absorbent body interposed between said topsheet and said backsheet; said topsheet includes longitudinal edges and a center wherein said topsheet is folded back over itself along each said longitudinal edge intermediate said center and each said longitudinal edge and bonded at least once thereto thereby forming both casings and flaps which act as fluid dams; an elastic band positioned in each said casing; said backsheet has first and second side and first and second ends; and an attachment means for allowing said diaper to be secured about its wearer comprising at least one strip of a selectively adhesive material applied to said first side adjacent to said first end of said backsheet and at least one other strip of selectively adhesive material applied to said second side adjacent to said second end of said backsheet.
 2. The diaper of claim 1, wherein said selectively adhesive material is selected from water-based latex adhesives, hot melt application paraffin- or rubber-based adhesives or any other adhesive having its adhesive characteristic limited to contact with the same or another selected adhesive.
 3. The diaper of claim 1, wherein said selectively adhesive material is a rubber-based adhesive utilizing a styrene butadiene styrene system.
 4. A disposable diaper, comprising:a fluid permeable topsheet, a backsheet and an absorbent body interposed between said topsheet and said backsheet; said topsheet includes longitudinal edges and a center wherein said topsheet is folded back over itself along each said longitudinal edge and bonded at least once thereto thereby forming casings and flaps which act as fluid dams; an elastic band positioned in each said casing; said backsheet has first and second sides and first and second ends; and an attachment means for allowing said diaper to be secured about its wearer comprising at least one strip of a hook and loop fastening system applied to said first side adjacent to said first end of said backsheet and at least one other strip of said hook and loop fastening system applied to said second side adjacent to said second end of said backsheet. 